04 Beetle losing coolant

I have a 04 beetle with a 2.0L with about 65K on it. Recently I have had to add coolant to it, twice in the last month. It doesn't overheat. It doesn't leave fluid on the ground. I pulled out 2 spark plugs, the easy ones, and they are both white. I thought they should be black/brown. I have also noticed that the car only gets around 22-25 mpg. Is this normal? I am thinking I may have a head gasket going out, but I am suprised that both end plugs would be burning white. Is it possible that the whole gasket is going out. Any help or suggestions would be much appreciated.

I had to add fluid again today. I checked in the reservoir tank while it was running and there is a very small amount of fluid coming back to it. Should this be large and noticable flow? I also noticed that is did have some pressure in the system when I opened the reservoir tank Does anybody have a suggestion?

Is the hose going into the top of the coolant jug the return line from the water pump? If so, what should be the flow rate of the coolant going into the jug. I measured mine and it is about 6 oz/min. This seems very low to me. Can anyone help me?

G'Day Zaktom, are you still having coolant problems? - if so, and from your diagnosis, I'd suggest going to a radiator shop and ask then to check the coolant for exhaust gas contamination - it's a simple procedure and can tell you if the head gasket is leaking. We have this in Australia.....guess your place would be the same. good Luck.

Edit....sorry, didn't check your latest post.

I decided to go after the water pump because of all of the threads on here about the plastic impeller. I found that the o-ring around the water pump was leaking. The plastic impeller of the water pump was fine. I did replace the water pump with a new one that had a metal impeller on it though.

Good that you found the fault and fixed it. Are your plugs still white? - we use E10 here which has 10% ethanol and the plugs are whiteish.....what fuel are you using?